******************* This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Dear all, I hope you are all well and you are enjoying Easter Sunday! I want to impose a time-dependent boundary condition, which derives from the rotation of a sphere about the y-axis. It would be easier to do this in spherical coordinates, but as far as I have understood Nektar takes cartesian coordinates. So, this is the expression I am implementing (where the radius of the sphere is 0.03 and t_s=0.05): <REGION REF="3"> <!-- Sphere --> <D VAR="u" USERDEFINEDTYPE="TimeDependent" VALUE="((2*t)/(sqrt((t_s-t)^2)+t_s+t))*(-1)*sqrt(0.03*0.03-y*y)*sin(atan2(x,z))" /> <D VAR="v" VALUE="0" /> <D VAR="w" USERDEFINEDTYPE="TimeDependent" VALUE="((2*t)/(sqrt((t_s-t)^2)+t_s+t))*sqrt(0.03*0.03-y*y)*cos(atan2(x,z))" /> <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" /> </REGION> However, I get this error: [lorenz-node01:46958] *** Process received signal *** [lorenz-node01:46958] Signal: Segmentation fault (11) [lorenz-node01:46958] Signal code: Address not mapped (1) [lorenz-node01:46958] Failing at address: 0x1f0000000c [lorenz-node01:46958] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x3ef20)[0x7f3c103c5f20] [lorenz-node01:46958] [ 1] /usr/lib/x86_64-linux-gnu/libMultiRegions.so.5.0.0(_ZN6Nektar12MultiRegions14DisContField3D34GenerateBoundaryConditionExpansionERKSt10shared_ptrINS_14SpatialDomains9MeshGraphEERKNS3_18BoundaryConditionsERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE+0x3f6)[0x7f3c12dcfd56] [lorenz-node01:46958] [ 2] /usr/lib/x86_64-linux-gnu/libMultiRegions.so.5.0.0(_ZN6Nektar12MultiRegions14DisContField3DC1ERKS1_RKSt10shared_ptrINS_14SpatialDomains9MeshGraphEERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEb+0x391)[0x7f3c12ddd7c1] [lorenz-node01:46958] [ 3] /usr/lib/x86_64-linux-gnu/libMultiRegions.so.5.0.0(_ZN6Nektar12MultiRegions11ContField3DC1ERKS1_RKSt10shared_ptrINS_14SpatialDomains9MeshGraphEERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEb+0x42)[0x7f3c12d9b9a2] [lorenz-node01:46958] [ 4] /usr/lib/x86_64-linux-gnu/libSolverUtils.so.5.0.0(_ZN6Nektar11SolverUtils14EquationSystem12v_InitObjectEv+0x1c16)[0x7f3c13543786] [lorenz-node01:46958] [ 5] /usr/lib/x86_64-linux-gnu/libSolverUtils.so.5.0.0(_ZN6Nektar11SolverUtils14UnsteadySystem12v_InitObjectEv+0x3c)[0x7f3c135865ac] [lorenz-node01:46958] [ 6] /usr/lib/x86_64-linux-gnu/libSolverUtils.so.5.0.0(_ZN6Nektar11SolverUtils15AdvectionSystem12v_InitObjectEv+0x36)[0x7f3c134cb346] [lorenz-node01:46958] [ 7] IncNavierStokesSolver(_ZN6Nektar15IncNavierStokes12v_InitObjectEv+0x31)[0x55ff2560ff01] [lorenz-node01:46958] [ 8] IncNavierStokesSolver(_ZN6Nektar24VelocityCorrectionScheme12v_InitObjectEv+0x2c)[0x55ff2561b7dc] [lorenz-node01:46958] [ 9] IncNavierStokesSolver(_ZN6Nektar24VelocityCorrectionScheme6createERKSt10shared_ptrINS_12LibUtilities13SessionReaderEERKS1_INS_14SpatialDomains9MeshGraphEE+0x116)[0x55ff2561f486] [lorenz-node01:46958] [10] /usr/lib/x86_64-linux-gnu/libSolverUtils.so.5.0.0(_ZN6Nektar12LibUtilities10NekFactoryINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEENS_11SolverUtils14EquationSystemEJRKSt10shared_ptrINS0_13SessionReaderEERKSA_INS_14SpatialDomains9MeshGraphEEEE14CreateInstanceES7_SE_SJ_+0xa1)[0x7f3c13522d51] [lorenz-node01:46958] [11] /usr/lib/x86_64-linux-gnu/libSolverUtils.so.5.0.0(_ZN6Nektar11SolverUtils6Driver12v_InitObjectERSo+0xbb5)[0x7f3c13522275] [lorenz-node01:46958] [12] /usr/lib/x86_64-linux-gnu/libSolverUtils.so.5.0.0(_ZN6Nektar11SolverUtils14DriverStandard6createERKSt10shared_ptrINS_12LibUtilities13SessionReaderEERKS2_INS_14SpatialDomains9MeshGraphEE+0x17c)[0x7f3c135347fc] [lorenz-node01:46958] [13] IncNavierStokesSolver(_ZN6Nektar12LibUtilities10NekFactoryINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEENS_11SolverUtils6DriverEJRKSt10shared_ptrINS0_13SessionReaderEERKSA_INS_14SpatialDomains9MeshGraphEEEE14CreateInstanceES7_SE_SJ_+0x114)[0x55ff255e7fa4] [lorenz-node01:46958] [14] IncNavierStokesSolver(main+0x2d1)[0x55ff255c6de1] [lorenz-node01:46958] [15] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7)[0x7f3c103a8b97] [lorenz-node01:46958] [16] IncNavierStokesSolver(_start+0x2a)[0x55ff255e254a] [lorenz-node01:46958] *** End of error message *** Segmentation fault (core dumped) Could anybody help me to understand what the problem could be? Thank you in advance for your help. Kind regards, Silvia